In-depth article | Academician Li Dadong teaches you how to address the challenges facing the refining industry!

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This post was last edited by llgq1252 on 2017-12-7 at 10:09. In 2016, China’s oil refining capacity reached 783 million tons per year, accounting for about 16% of the world’s total oil refining capacity, placing it second in the world. At the same time, through decades of independent innovation in petroleum refining technology, our country has gradually developed a complete technical system; with such independent technologies, it is possible to build modern refineries with a capacity of tens of millions of tons. However, last year only 540 million tons of crude oil were actually processed, and a total of 348 million tons of refined products such as gasoline, diesel, and kerosene were produced. The average operating capacity of the refineries was 69.1%, indicating an obvious excess capacity. From the perspective of market demand, although the consumption of refined oil continues to show an upward trend, changes have occurred: the rigid demand for gasoline and kerosene is growing rapidly, while the peak in diesel consumption has passed, leading to a decline in its usage. The diesel-to-gasoline ratio in 2016 dropped to 1.39, and it is expected to fall further to 1.2 or even 1.1 by 2020. Looking at the quality of refined oil, the pace of improvement in such oil in our country is accelerating continuously. As the implementation date for National Standard V gasoline and diesel across the country was advanced by one year, our country has already adopted Standard V this year. Meanwhile, Beijing began implementing the Beijing VI standard in January this year, which requires a significant reduction in the levels of benzene, aromatics, and olefins in gasoline. The improvement of oil quality continues; China will implement Phase A standards for National VI gasoline and National VI diesel standards in 2019, while Phase B standards for National VI gasoline will come into effect by 2023. Compared to National V gasoline, the sulfur content specification for National VI remains unchanged at 10 ppm, which is in line with the Euro VI standard. The changes in gasoline standards are mainly reflected in the benzene content and aromatic hydrocarbon content: the benzene content decreased from 1% to 0.8%, which is slightly lower than the Euro VI standard (1%) ； The aromatic content decreased from 40% to 35%, which is equivalent to the Euro VI standard ； The olefin content is required to decrease from 24% to 18% in stage A, and further to 15% in stage B, gradually approaching the Euro VI standard of 10%. Compared to National Standard V diesel, National Standard VI diesel still has a sulfur content of 10 ppm, which is on par with the Euro VI standard ； The content of polycyclic aromatic hydrocarbons decreased from 11% to 7%, slightly below the Euro VI standard (8%). Based on the actual equipment used in domestic production, it should not be a problem to reduce the content of polycyclic aromatic hydrocarbons in the product to below 7% using a diesel hydrogenation unit. Therefore, the main task for China’s refining industry in the future is to control the rapid growth of refining capacity, while striving to adjust the structure of refineries and products, making more efficient use of oil resources, promoting cleaner production processes and an improvement in product quality, reducing the ratio of diesel to gasoline, and strengthening the integration of oil processing and chemical production, in order to create a product structure that meets market demands. To accomplish the aforementioned tasks, we need to explore the future development path of the oil refining industry. As a company, the first thing to consider is what kind of oil to refine in the future. Among the crude oil processed in our country today, imported crude oil accounts for over 65%, and this proportion is set to rise in the future. Therefore, when deciding what type of crude oil to process, we must take into account the remaining exploitable reserves worldwide. Globally, the remaining recoverable oil reserves will last for a long time, but their quality is deteriorating. The quality of crude oil worldwide shows a trend of an increasing proportion of sulfur-containing and high-sulfur crude oils, as well as an increasing proportion of heavy crude oils. Data shows that in 2010, global crude oil production was 3.914 billion tons, of which sulfur-containing and high-sulfur crude oils accounted for 75%. High-sulfur crude oil with a sulfur content of over 1.5% accounts for about 70% of the remaining exploitable reserves worldwide. Whether from the perspective of resources or efficiency, refining low-quality crude oil is an inevitable choice for the refining industry in the future. To cope with such market changes, the refining industry should specifically improve key technologies such as the efficient utilization of oil resources, the production of clean fuels, higher gasoline yields, and the integration of oil refining and chemical processing (end). Today’s technology recommendations: 1. Technologies for producing more gasoline and jet fuel. The consumption pattern in China’s refined oil market has changed, with diesel consumption on the decline; therefore, attention should be paid to technologies that enable the production of more gasoline and jet fuel. For decades, catalytic cracking has brought significant benefits to the oil refining industry by producing gasoline. However, the associated problems cannot be ignored, such as flue gas desulfurization and carbon dioxide emissions. The approach to solving this problem is to subject all the feedstocks for catalytic cracking to hydrogenation. After hydroprocessing, the amount of product gasoline increases significantly, the diesel-to-gasoline ratio decreases, and flue gas SOx (sulfur oxides) and carbon dioxide are greatly reduced. Against the backdrop of a reduced diesel-to-steam ratio and increasing market demand for BTX (benzene, toluene, xylene), the cracking of catalytic diesel (LCO) to produce gasoline or aromatics is also one of the ways to adjust the product structure. In response to the high content of polycyclic aromatic hydrocarbons in catalytic diesel, the China Academy of Petroleum Sciences has developed the hydrocracking (RLG) technology and the hydrotreating-catalytic cracking technology (LTAG), which can effectively convert the polycyclic aromatic hydrocarbons in catalytic diesel into gasoline components or monocyclic aromatic hydrocarbons. The Institute of Stone Sciences has developed the specialized refined catalyst RN-411 for RLG technology, which enables maximum retention of monocyclic aromatics during denitration and polycyclic aromatic hydrocarbon saturation; it has also developed the specialized cracking catalyst RHC-100, which facilitates effective ring opening of naphthalenes, effective cleavage of side chains in alkylbenzenes, and maximum retention of BTX components. Another important point is that no olefins were detected in the heavy gasoline produced by Shanghai Petrochemical’s 650,000 tons per year RLG plant, which is significant for ensuring that the product meets the new oil quality standards. To produce aviation kerosene from straight-run kerosene fractions, the main issue that needs to be addressed is desulfurization. The hydrodesulfurization of aviation kerosene technology (RHSS) developed by the Institute of Rock and Mineral Sciences has seen the development of a second-generation catalyst along with a corresponding hydrodesulfurization process, which can **improve processing capacity or the adaptability to various feedstocks. This technology removes acidic components such as mercaptans, naphthenic acids, and carboxylic acids from straight-run jet fuel through a hydrocatalytic reaction. It also improves the color of the product, reduces the total sulfur content, and increases the flash point of aviation kerosene. 2. Clean fuel production technology: In recent years, there has been an increasing emphasis on environmental protection in society, and environmental standards have kept rising. Refineries owned by Sinopec have been upgrading their facilities, with one of the main goals being to reduce the sulfur content in refined petroleum products. Regarding gasoline, due to its low investment requirements and simplicity of operation, the dominant technology in the world today is selective hydrodesulfurization of catalytically cracked gasoline. The RSDS technology developed by the Institute of Rock Mechanics has been industrially applied in more than a dozen units, and the technology has evolved to its third generation; when producing Grade V gasoline, it results in a lower octane number loss of 0.5 to 1.2 units compared to the second-generation technology. The plant at Shanghai Petrochemical that utilizes third-generation RSDS technology came online in June 2014 to produce gasoline meeting National V standards; it has been operating continuously ever since, with sulfur content remaining below 10 ppm and an octane loss of around 0.5. As can be seen from the **standards, the sulfur content in gasoline meeting National Standard V is already on par with that required by European Standard VI. When upgrading to National Standard VI, the sulfur content requirement remains unchanged, but higher demands are placed on the levels of olefins and aromatics. To meet the requirements of the new standards while maintaining a high octane rating, it is necessary to add isomerized alkane components, and this is a situation that companies will have to face in the future. The main technologies for producing heteroalkanes today are alkylation technology and C5/C6 isomerization technology. When developing the second-generation C5/C6 isomerization technology, the Institute of Stone Sciences developed super-acid catalysts. Sinopec upgraded the existing isomerization unit at Zhanjiang Dongxing Petrochemical using second-generation C5/C6 isomerization technology, adding a hydrogenation pretreatment unit and a drying unit. The original zeolite-type catalysts were replaced with super-acid-type isomerization catalysts, reducing their quantity from 18 tons to 13.5 tons. To date, the unit has been operating continuously for over a year, and the octane rating of the product after a single pass has increased from 82 before the modification to 85. Sinopec’s ZCA-1 solid acid alkylation technology, which possesses independent intellectual property rights, uses isobutane and butylene as raw materials. By employing solid acid catalysts and an efficient fixed-bed process, it produces clean alkylated gasoline, thereby avoiding the safety and environmental issues associated with liquid acid alkylation; it represents a green alkylation process technology. Based on the data from 11,000 hours of operation of medium-scale units that employ this alkylation technology, the research octane number (RON) averaged 95.6, the motor octane number (MON) averaged 92.5, the olefin conversion rate was 100%, and the stability was very good. Subsequently, industrial side-line tests were conducted at Yanshan Petrochemical, and data from 3600 hours of stable operation showed an average RON of 96.5, indicating satisfactory performance. For diesel, the ultra-deep desulfurization of diesel technology (RTS) can be used. This technology uses non-precious metal hydrogenation catalysts with high desulfurization and hydrogenation capabilities, featuring high space velocity and good product quality. Pilot test results show that crude oil with a sulfur content as high as 9600 ppm can be refined into diesel products with a sulfur content of 6 ppm. Since its industrialization in 2012, RTS technology has been applied in 9 industrial units, among which the RTS unit at Takahashi Petrochemical has been in operation for over 3 years with stable product quality. 3. Technologies for efficient utilization of petroleum resources: The key to efficient utilization of petroleum resources lies in finding ways to convert residue oil into light hydrocarbons to the greatest extent possible. Several technologies are involved here: first, the fixed-bed residue hydrogenation technology (RHT); second, the two-stage combination technology of residue hydrogenation (RHT) and heavy oil catalytic cracking (RICP); third, the integrated technology of FGO selective hydrogenation and selective catalytic cracking (FCC) for producing more light oils (IHCC); fourth, the combination technology of shallow solvent deasphalting – deasphalted oil hydrogenation – catalytic cracking (SHF). Generally, when the contents of metals such as nickel (Ni) and vanadium (V) in residue are less than 200 ppm, it is recommended to use RICP or IHCC techniques ； When it is greater than 200 ppm, it is recommended to use SHF technology. One of the key points and challenges in the RHT technology developed by the Institute of Rock Mechanics is to convert asphaltenes into small molecules in order to prevent the formation of carbon deposits. A thorough understanding of the chemical structural characteristics of asphaltenes contributes to achieving efficient conversion. On this basis, the Institute of Rock Mechanics developed the idea of creating large-pore channels to facilitate the diffusion of asphaltenes. To date, the Institute of Petrology has developed three generations of RHT catalysts, which have been applied in over 50 industrial units both within and outside Sinopec’s system. Combining RHT technology with heavy oil catalytic cracking technology is a conventional practice; traditionally, it is a one-way combination, meaning that the catalytically recycled oil circulates within the catalytic cracking process itself. However, there are some issues with the one-way combination, as most of the recycled oil consists of polycyclic aromatic hydrocarbons; when fed directly into catalytic cracking, it mainly results in coke and dry gas ； In the case of residue hydrogenation, due to the large molecular weight and high viscosity of the residue, the reaction rate is very low; simultaneously, during this process, asphaltenes continue to precipitate and form carbon deposits. Based on this, the China Institute of Petroleum Science developed a two-way combined RICP technology that incorporates heavy cycle oil (HCO) into the residue hydrogenation feed, thereby increasing the solubility of asphaltenes in the hydrogenated product and effectively reducing catalyst coking, while enhancing reaction activity and stability. After the RICP technology was applied at Anqing Petrochemical in 2013, the desulfurization rate, denitrification rate, and residual carbon removal rate increased significantly. In terms of product distribution, liquefied gas and gasoline increased by 2.5 and 0.9 percentage points respectively, while oil slurry and carbon deposits decreased by 3.5 and 0.6 percentage points respectively. The total liquid yield increased by 3.3 percentage points, and the average carbon content decreased significantly when the catalyst was removed. The integrated technology of FGO selective hydrogenation and selective catalytic cracking (IHCC) for producing light oil addresses the issue of a sharp increase in dry gas and coke after the conversion rate in conventional catalytic cracking exceeds 70%. In 2015, Sinopec made significant efforts to send the tail oil from the VRDS unit at Shanghai Petrochemical to Qingjiang Petrochemical for industrial testing. The results show that, compared with the conventional catalytic cracking approach, the light oil yield using the IHCC approach increases by 10 percentage points, with no slurry produced; meanwhile, dry gas and coke decrease by 1.62 and 2.05 percentage points, respectively. For the SHF technology used in the refining of crude oil with high heavy metal content, heavy solvents such as butane or pentane are employed to remove asphaltenes and heavy metals, resulting in a high yield of deasphalted oil (DAO) of over 80%. Due to the low content of heavy metals and asphaltenes in deasphalted oil, it can undergo hydrogenation at medium pressure to produce high-quality catalytic cracking feedstock, thereby enabling the production of clean gasoline with low sulfur and low olefin content. Furthermore, the investment in the deasphalted oil hydrogenation unit is only 30–40% of that for the residue hydrogenation unit, and the catalyst consumption is only 1/4 of the latter, resulting in good economic benefits.